The present invention relates to a design support apparatus for a circuit diagram of a circuit including a directional coupler using crosstalk and for a circuit layout diagram of the same, a design support tool, a method of designing the circuit, and a circuit board.
As a technology for transferring data among a plurality of modules, a bus system used for data transfer in a computer has been known. In this bus system, the plurality of modules are connected by a common bus, and data is transferred time-divisionally among the modules by use of this bus as a data transmission line. Such a kind of bus is usually constituted by a wiring for an address signal, a wiring for a data signal, a wiring for a control signal and the like.
In the bus system, as a connection style of the bus and the module, the one in which the modules are coupled to the bus directly or through resistors and the one in which by use of crosstalk, the modules are coupled to the bus so as to be uncontacted with each other have been known. The style in which by use of the crosstalk, the modules are connected to the bus so as to be uncontacted with each other is described in Japanese Patent Application Laid-Open No. 2000-132290.
When the crosstalk is utilized, as shown in FIG. 35, for example, a driver signal line 3502 is coupled to a driver 3501, a receiver signal line 3512 is coupled to a receiver 3511, and a part 3504 of the driver signal line 3502 and a part 3514 of the receiver signal line 3512 are arranged in parallel with a constant interval. The parts in parallel with each other are a main line 3504 and a stub line 3514, and a directional coupler (coupler) 3500 is constituted by these wirings. In this coupler 3500, crosstalk is generated by a signal from the driver 3501. In the crosstalk signal, there are rear crosstalk generated in the reverse direction to a signal direction in the main line 3504 and front crosstalk generated in the same direction as the signal direction in the main line 3504. In the constitution shown in FIG. 35, the rear crosstalk is sent to the receiver 3511 via the stub line 3514, and the front crosstalk is absorbed by a termination resistor 3513 coupled to the stub line 3514. A waveform of a signal from the driver 3501 is absorbed by a termination resistor 3503 coupled to the main line 3504. Thus, unnecessary crosstalk due to the reflection of a drive signal does not occur on the stub line 3514.
In general, when crosstalk is generated between two ordinary wirings, the crosstalk becomes signal noise. Therefore, in order to prevent this crosstalk, the two wirings are made to be apart from each other with an interval more than a certain length. On the contrary, in the above described technologies, the interval between the two wirings is narrowed, and crosstalk is intentionally generated. A signal is transferred from one wiring to the other wiring without contacting them with each other.
By the way, a circuit diagram of a bus system utilizing the crosstalk was conventionally illustrated as shown in FIG. 36.
In this circuit diagram, reference numerals 611 and 612 denote functional components. Terminals D1, D2 and CLK are provided in the functional component 611, and wirings 621, 622 and 623 are provided so as to extend respectively from the terminals D1, D2 and CLK. Terminals d1, d2 and clk are provided also in the functional component 612, and wirings 641, 642 and 643 are provided so as to extend respectively from the terminals d1, d2 and clk.
In FIG. 36, portions 3601, 3602 and 3603 are respectively formed as couplers, and indirect connections of the terminals D1 and d1, the terminals D2 and d2, and the terminals CLK and clk are intended. In FIG. 36, though the coupler portions 3601, 3602 and 3603 are surrounded by the circles, the circles are merely drawn for the sake of convenience to facilitate understanding of the positions of the coupler portions. In the conventional circuit diagram, the coupler is simply treated as two different wirings, and the coupler portion is not illustrated.
When a circuit layout diagram is illustrated by use of the above described circuit diagram, the circuit layout diagram as shown in FIG. 37 is prepared in the prior art in such a manner that two wirings forming a coupler is anew selected among many wirings illustrated in the circuit diagram, and parts of the selected two wirings are arranged in parallel with a certain interval. Note that FIG. 37 illustrates a layout diagram of the coupler portions 3601, 3602 and 3603 in FIG. 36.
However, in the foregoing prior art, since the couplers are treated as a mere wiring in the circuit diagram, that is, since illustrations of the coupler are not made in the circuit diagram, two wirings forming a coupler must be anew selected among many wirings illustrated in the circuit diagram when a circuit layout diagram is drawn with reference to this circuit diagram, and moreover recognition of a correlation between the circuit diagram and the circuit layout diagram takes a lot of trouble.
Particularly, when crosstalk is used in a bus line, the number of the couplers is equal to the product of a xe2x80x9cbus widthxe2x80x9d and the xe2x80x9cnumber of functional componentsxe2x80x9d. For example, when the bus width is 64, and the number of the functional components is 9, the number of the couplers is as large as 512. Therefore, a lot of trouble is required to recognize the correlation between the circuit diagram and the circuit layout diagram.
Furthermore, normally, after the circuit layout diagram is once completed, intervals between many wirings are checked by use of a design support apparatus. If the contravention against a wiring rule is found out, the wiring layout is anew prepared. In this case, when a coupler 800 exists in the circuit layout diagram as shown in FIG. 37, an interval 3701 between two wirings forming the coupler 800 contravenes the wiring rule. Accordingly, when it is tried to check the interval 3701 visually without the use of the design support apparatus, labor for checking the interval 3701 is immense. Moreover, even when an interval 3702 between two wirings which do not constitute a coupler is narrow and crosstalk between these wirings occurs, there is a fear that the crosstalk cannot be found out.
In other words, the prior art has a problem that the preparation of the layout diagram of the circuit including the coupler takes a lot of trouble.
This application was made while focusing on the above described problems of the prior art, an end of this application is to provide the invention according to a design support apparatus for a circuit diagram and a layout diagram, which is capable of reducing the number of design steps for designing the layout diagram of a circuit including couplers, a system comprising the design support apparatus, a design support tool for operating a computer for a design support, and a design method of the same. This application provides also the invention according to a circuit board which is designed by the above-mentioned design support system or the design support tool.
A first design support apparatus for achieving the foregoing end is a design support apparatus for a circuit diagram which illustrates connections of components in a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver, comprising:
symbol storage means for storing various symbols, each being previously determined for corresponding one of various components including the directional coupler;
symbol arrangement means for accepting a symbol to be arranged among various symbols stored in the symbol storage means and for accepting an arrangement position of the symbol to arrange the symbol at the arrangement position accepted; and
circuit diagram information storage means for storing the symbol arranged by the symbol arrangement means and the arrangement position of the symbol.
A second design support apparatus to achieve the foregoing end is a design support apparatus for a circuit layout diagram which illustrates arrangements of components and arrangements of connections of the components in a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver, comprising:
attribute information acceptance means for accepting coupler attribute information including at least a parallel signal line length of the directional coupler and a signal line interval thereof;
component arrangement means for arranging a part of the first signal line and a part of the second signal line, which constitute the directional coupler, as the directional coupler based at least on the coupler attribute information accepted by the attribute information acceptance means;
wiring interval check means for checking an interval between two wirings in accordance with a rule previously determined; and
check object extraction means for accepting check objects checked by the wiring interval check means, for deciding whether the directional coupler exists in the accepted check objects, and for extracting the parts of the first and second signal lines constituting the directional coupler, which are checked as one directional coupler by the wiring interval check means, as well as for excepting an interval between the parts of the first and second signal lines from the check objects, when the directional coupler exists in the accepted check objects.
Here, the second design support apparatus may further comprise circuit diagram information acceptance means for accepting information of a circuit diagram, in which a plurality of components including the directional coupler are represented by symbols and connections of the components are illustrated,
wherein upon acceptance of an arrangement relating to a symbol in the circuit diagram information accepted by the circuit diagram information acceptance means, the component arrangement means decides based on the coupler attribute accepted by the attribute information acceptance means whether the symbol is the directional coupler, and arranges the parts of the first and second signal lines constituting the directional coupler, when the component arrangement means decides that the symbol is the directional coupler.
A design support system to achieve the foregoing end is a design support system, comprising:
the first design support apparatus; and
the second design support apparatus,
wherein the second design support apparatus accepts the circuit diagram prepared by the first design support apparatus and prepares the layout diagram based on the circuit diagram.
Here, the design support system may further comprise a manufacture data preparation apparatus for preparing circuit manufacture data based on information of the layout diagram.
A design support tool to achieve the foregoing end is a design support tool for allowing a computer to execute a design support of a circuit diagram illustrating connections of various components in a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver,
the tool having symbol data stored in a first storage area of the computer, the symbol data being related to a shape of a symbol previously determined for each of the components including the directional coupler, and
the tool allowing the computer to execute symbol arrangement procedures for accepting symbols to be arranged among various symbol data stored in the first storage area as well as for accepting arrangement positions of the symbols, and for arranging the symbols at the arrangement positions accepted; and
circuit diagram information storage procedures for storing the symbols arranged in the symbol arrangement procedures and the arrangement positions of the symbols in a second storage area of the computer.
A second design support tool to achieve the foregoing end is a design support tool which allows a computer to execute a design support of a layout diagram illustrating arrangements of components and arrangement of connections among the components in a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver,
the tool allowing the computer to execute attribute information acceptance procedures for accepting coupler attribute information including at least a parallel signal line length of the directional coupler and a signal line interval thereof;
component arrangement procedures for arranging a part of the first signal line and a part of the second signal line, which constitute the directional coupler, as the directional coupler based at least on the coupler attribute information accepted in the attribute information acceptance procedure;
wiring interval check procedures for checking an interval between two wirings in accordance with a rule previously determined; and
check object extraction procedures for accepting check objects checked by the wiring interval check procedures, for deciding whether the directional coupler exists in the accepted check objects, and for extracting the parts of the first and second signal lines constituting the directional coupler, which are checked as one directional coupler in the wiring interval check procedures, as well as for excepting an interval between the parts of the first and second signal lines from the check objects, when the directional coupler exists in the accepted check objects.
Here, in the second design support tool,
the attribute information acceptance procedures may accept coupler attribute information containing identification information of the directional coupler as the coupler information; and
the check object extraction procedures may decide based on the identification information of the coupler attribute information whether the directional coupler exists in the check objects.
Moreover, the second design support tool may be a tool allowing the computer to execute circuit diagram information acceptance procedures for accepting information of a circuit diagram, in which a plurality of components including the directional coupler are represented by symbols and connections of the components are illustrated,
wherein upon acceptance of an arrangement relating to a symbol in the circuit diagram information accepted by the circuit diagram information acceptance procedures, it is decided in the component arrangement procedures based on the coupler attribute accepted in the attribute information acceptance procedures whether the symbol is the directional coupler, and the parts of the first and second signal lines constituting the directional coupler are arranged, when it is decided that the symbol is the directional coupler.
Moreover, in the second design support tool, when information to the effect that the parts of the first and second signal lines constituting the directional coupler must be a straight line and must not have a bent portion exists as the coupler attribute information accepted in the attribute information acceptance procedures, components other than the parts of the first and second signal lines may be moved to keep linearities of the parts of the first and second signal lines without allowing the parts of the first and second signal lines to detour other components in spite that necessity of detouring of the parts of the first and second signal lines occurs due to existence of other components in a step for arranging the parts of the first and second signal lines in the component arrangement procedures.
Moreover, in the second design support tool, when information to the effect that the parts of the first and second signal lines constituting the directional coupler are overlapped with each other in a direction from one plane of a circuit board to the other plane thereof exists as the coupler attribute information accepted in the attribute information acceptance procedures, the parts of the first and second signal lines may be arranged so as to be overlapped with each other in the direction in the component arrangement procedures.
A design method to achieve the foregoing end is a method of designing a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver, comprising the steps of:
deciding a symbol, which is to be arranged, among symbols each of which is previously determined for corresponding one of various components including the directional coupler as well as deciding an arrangement position of the symbol, and arranging the symbol as the decided arrangement position, thus preparing a circuit diagram;
storing the symbol arranged in preparing the circuit diagram and the arrangement position of the symbol;
deciding coupler attribute information including at least a parallel signal line length of the directional coupler and a signal line interval thereof;
arranging parts of the first and second signal lines constituting the directional coupler as the directional coupler based at least on the coupler attribute information set in deciding the coupler attribute information when a component arranged in a layout diagram is a symbol of the directional coupler among the symbols in the circuit diagram;
checking an interval between two wirings in accordance with a rule previously determined; and
accepting check objects checked as to the interval between the two wirings, deciding whether the directional coupler exists in the accepted check objects, and extracting the parts of the first and second signal lines constituting the directional coupler, which are checked as one directional coupler in checking the interval between two wirings, as well as excepting an interval between the parts of the first and second signal lines from the check objects, when the directional coupler exists in the accepted check objects.
A second design method to achieve the foregoing end is a method of designing a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver by using a computer, comprising the steps of:
storing information regarding the directive coupler, the information being defined under conditions in which the directional coupler generates the crosstalk signal; and
arranging parts of the first and second signal lines in a layout diagram based on the information regarding the directional coupler upon accepting instruction of arranging the directional coupler, the parts constituting the directional coupler.
Here, the information regarding the directional coupler preferably includes identification information for identifying the directional coupler, lengths of the parts of the first and second signal lines constituting the directional coupler and an interval between the parts of the first and second signal lines constituting the directional coupler. In this case, the interval may be a maximum value of an interval with which the crosstalk signal occurs between the parts of the first and second signal lines. Note that the interval may be appropriately changed in a range not exceeding the maximum value.
A circuit board designed by the invention relating to the design support is a circuit board comprising:
a driver outputting a signal;
a first signal line coupled to the driver;
a plurality of receivers, each of which receives a crosstalk signal based on the signal from the driver;
second signal lines respectively coupled to the plurality of receivers; and
a circuit board body on which the driver, the first signal line, the receivers, and the second signal lines are provided,
wherein a plurality of directional couplers, each of which is constituted in such a manner that a stub line composed of a part of the second signal line and a main line composed of a part of the first signal line are arranged in parallel with each other, are provided thereon, and
wherein the main line and the stub line constituting each of the directional couplers are a straight line and in parallel with each other.
Here, in the circuit board,
the three or more receivers and the directional couplers of the same number as the receivers are provided,
the main line and the stub line, which constitute each of the plurality of directional couplers, extend in the same direction,
the three or more receivers are arranged in the direction to which the main line and the stub line extend, a spot in which an interval between the receivers adjacent to each other is longer than lengths of the main and stub lines exists and a spot in which an interval between the receivers adjacent to each other is shorter than the lengths of the main and stub lines exists, and
any of the plurality of directional couplers may be arranged in at least one of the spots in which the interval is longer than the lengths of the main and stub lines.
In this case, the main and stub lines constituting the plurality of directional couplers preferably overlap in a direction from one plane of the circuit board body to the other plane thereof. In such a circuit board, it is preferred that the circuit board body has an inner layer board, the main line constituting the directional coupler is arranged on one plane of the inner layer board, and the stub line constituting the directional coupler is arranged on the other plane of the inner layer board.